Bats need trees as maternity wards, to save us from bugs

This handsome fellow is shown being held in 2010 by a researcher at the Old… (Heritage Conservancy,…)

April 02, 2013|Paul Carpenter

The abandoned Durham Iron Mine in upper Bucks County once belonged to William Penn and, in 1999, it served as the winter hibernation home for up to 17,000 bats, after they had dined on nearly 12 tons of airborne bugs in warmer months.

Nine years later, according to a story in The Morning Call last week, that mine was down to about 4,000 bats, and now, five years after that, there are just seven.

Multiply that decline in the bat population by the hundreds of hibernation sites in this region, and you'll see why we may be tormented by mosquitoes and other bugs in coming summers, and farmers may see higher percentages of their crops ruined.

Last week's story focused largely on concerns that Pennsylvania's forestry industry could suffer a crimp in profits if there are restrictions on the number of trees that can be chopped down. Preserving trees was one of the ideas being considered to deal with a fungus that has wiped out many bats in various parts of America and Canada.

"Pennsylvania has had the most precipitous decline," the story said. A proposal to put bats on a list of endangered species "could lead to a ban on tree removals" to protect the remaining bats' summer shelters. Forestry industry lobbyists were mobilized in Harrisburg, the bats be damned.

This week, I got in touch with Scott Weidensaul, an acclaimed naturalist and researcher and the author of more than two dozen books. We've known each other since our days at The Pottsville Republican newspaper. He said there are hibernation sites faring even worse than Durham Mine. One colony of as many as 300,000 bats in western Pennsylvania is down to 138.

"I can't think of another case where a population has collapsed so rapidly," he said, and he was not just talking about bats. "It's a terrifying example of how a single pathogen can upset everything."

The chief culprit is a fungus called "white-nose syndrome" and it does not affect all bats, just those that hibernate in winter. Migratory bats are not harmed by the fungus, Weidensaul said, "but they are being killed by the thousands by wind turbines." (I've had plenty to say about the wind turbine scam, a laughably inefficient energy source unless propped up with taxpayer subsidies, but I'll save the bat slaughter issue for another day.)

Weidensaul said the fungus probably was brought to America by cave explorers in Europe, who carried it on their shoes or other clothing when they later explored American caves. It did not harm European bats because they had developed an immunity that did not exist in American bats.

The real expert on the bat problem, he said, is Aura Stauffer of the Bureau of Forestry in the Pennsylvania Department of Conservation and Natural Resources.

"It [the fungus] causes a great deal of irritation to the bats and they were waking up in the winter months," she told me. "Typically, when bats hibernate, they fill up their body fat." When roused from their long winter sleep, they use up fat reserves, cannot find any bugs to replenish them, and starve or succumb to dehydration.

"It's spreading all over the place," Stauffer said, and sent me a map showing occurrences mainly along the Appalachians but as far north as mid-Quebec, as far south as Georgia and as far west as Missouri.

The map pinpoints Schoharie County, N.Y., near Albany, as the first place the fungus was detected, in 2006, although the worst concentrations were soon found in Pennsylvania. "It's pretty awful," Stauffer said. "It's at a point now where everyone's trying to figure out what to do."

One thing being emphasized is the need to save bats that have thus far survived. To do that, shelter needs to be available for females when they have their young in the summer. That's where the trees come in.

"When the bats leave the caves, they form bat colonies, sometimes in trees," Stauffer said. An example of a great maternity tree, she said, is the shagbark hickory, a source of expensive wood for the lumber industry.

Many people are trying to provide "bat boxes" that are hung or mounted in sunny areas close to forested areas, which give bats protection from predators. Plans and instructions for the boxes are available from the Pennsylvania Game Commission.

I also checked with the Pennsylvania Forest Products Association, which sent me a release saying it is "deeply concerned about this proposal's targeting of timber removal and other forestry activities."

Curbs on "timber harvesting," the release said, "will devastate Pennsylvania's forest products industry and the owners of working forests." It said such action must be "based on sound science" and "there is no data or research to suggest that timbering or forestry activities are linked to WNS." (That is correct. White-nose syndrome is not caused by a lack of trees, but trees are needed to help bats make a comeback.)

Some politicians may think only of the commercial special interests who fill their campaign coffers, but the bat problem goes beyond typical tree-hugger fretting.

Unchecked plagues of insects and serious damage to agricultural crops may turn out to be problems more serious than depriving certain business interests of some of their profits. Think of it in terms of a few tons of hungry mosquitoes swarming around your yard in coming years.